In a semiconductor device such as a gallium nitride-based High Electron Mobility Transistor (HEMT), a source electrode is disposed on a gallium nitride layer, and a drain electrode is disposed adjacent and to the side of the source electrode. In addition, a gate electrode is located between the source electrode and the drain electrode. Further, in order to suppress electric field concentration on the gate electrode, a field plate electrode which is electrically connected to the gate electrode may be provided.
Here, the field plate electrode, the source electrode, and the drain electrode are formed by different processes. For this reason, the number of process steps in a manufacturing process is not able to be reduced, and cost reduction in a semiconductor device is not able to be realized.